PROJECT SUMMARY/ABSTRACT Inability to perform Activities of Daily Living (ADLs) is a primary cause of reduced quality of life for the millions of Americans living with AD/ADRD and is an important barrier to living independently for these older Americans. Older adults with AD/ADRD are at particular risk of functional decline and death following hospitalization. Sarcopenia, or aging-related declines in skeletal muscle mass and strength is likely to be an important risk factor for hospital-associated ADL disability in older adults, and this relationship may be particularly relevant in older adults with AD/ADRD. A key barrier to understanding of the contribution of sarcopenia to the development of hospital-associated ADL disability among those with AD/ADRD, is the need for measures of muscle mass that are feasible in these patients in the acute care setting. Bedside portable ultrasound-based measures of thigh muscle architecture are reliable and practical, correlate well with thigh muscle strength in acutely-ill patients, and are already being successfully applied by my group to assess rectus femoris cross-sectional area (RFCSA) in older adults hospitalized with sepsis. This administrative supplement proposal is an extension of the existing K23 grant (5K23AG058756-01; ?Sarcopenia as a Predictor of Hospital Associated Disability in Older Adults?), which was awarded to determine the ability of sarcopenia, operationalized as muscle mass and strength, to predict the development of activity of daily living (ADL) disability among hospitalized older adults. The additional studies proposed herein will expand the current research by adding an AD/ADRD focus that will investigate the use of bedside portable ultrasound measures in AD/ADRD patients with sepsis ((n= 25 men (13 with dementia), 25 women (13 with dementia)) with the overall objective of determining relationships of ultrasound-based measures of thigh muscle architecture with functional outcomes of hospitalization in AD/ADRD patients.